[amsat-bb] Re: 1.2ghz helix

Edward Cole kl7uw at acsalaska.net
Tue Oct 28 23:15:57 PDT 2008


That is what I have used with great success.  Some folks make a 
curved line but I just used some 1/4 inch brass strap that I cut to 
fit one quarter turn from the coax connector to the beginning of the 
helix wire (I use 12ga. house wire with insulation stripped 
off).  The connector end of the strip line has a hole drilled to fit 
the N-connectort pin and is soldered as close to ground and not short 
out.  The other end is only about 1/4 inch farther from ground.  I 
drill a hole there for the 12ga wire to connect.

I am using this for a 3-1/2 turn helix feed on 1296 and a 6-turn feed for 2400.

73, Ed - KL7UW

At 06:58 PM 10/28/2008, w7lrd at comcast.net wrote:
>I am almost finished with a 16 turn helix for 1.2ghz.  I am not sure 
>of what type of matching I should use.  Some of designs I have  seen 
>use a flat tab on the first 90 degrees of the helix.  What size 
>should it be?  Is there a better way?  I have a bird 43 with a 1.2 
>slug for tuning.
>73 Bob W7LRD
>"if this were easy, everyone would be doing it"
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